This invention relates to a process for purifying 1,1,1-trifluoro-2-chloro-2-bromoethane.
1,1,1-TRIFLUORO-2-CHLORO-2-BROMOETHANE IS KNOWN UNDER THE NAME "Halothan" as a valuable inhalation anaesthetic. Depending on the method of its manufacture it may contain small amounts of impurities, such as compounds of the type CF.sub.3 -- CX = CY -- CF.sub.3 in which X represents hydrogen, chlorine or bromine and Y represents chlorine or bromine. Such impurities can, however, not be tolerated in Halothan if it is to be used as an anaesthetic, and, therefore, they must be removed. Removal by distillation can be performed only with great difficulty. Consequently, a number of refining processes have been described in which contaminated Halothan is purified by treatment with anhydrous aluminum halides, as disclosed in German "Offenlegungsschrift" No. 1,543,089 or aqueous permanganate solution, as disclosed in German "Offenlegungsschrift" No. 1,543,101. In these processes, however, the great sensitivity of aluminum halides to moisture is disadvantageous, or, if potassium permanganate is used, the refining action is not as good.
It has now been found that 1,1,1-trifluoro-2-chloro-2-bromoethane which is contaminated mainly with compounds of the general formula CF.sub.3 -- CX = CY -- CF.sub.3 (X = hydrogen, chlorine or bromine, Y = chlorine or bromine) can be purified by putting it into intimate contact with one or more organic amines and recovering in a known manner the 1,1,1-trifluoro-2-chloro-2-bromoethane which has thus been freed of the impurities.